The direct introduction of a normal, functional gene into a living animal has been studied as a means for replacing defective genetic information. In some studies, DNA is introduced directly into cells of a living animal without the use of a viral particle or other infectious vector. Nabel, E. G., et al., (1990) Science 249:1285–1288, disclose site-specific gene expression in vivo of a beta-galactosidase gene that was transferred directly into the arterial wall in mice. Wolfe, J. A. et al., (1990) Science 247:1465–1468, disclose expression of various reporter genes that were directly transferred into mouse muscle in vivo. Acsadi G., et al., (1991) Nature 352:815–818, disclose expression of human dystrophin gene in mice after intramuscular injection of DNA constructs. Wolfe, J. A., et al., 1991 BioTechniques 11(4):474–485, which is incorporated herein by reference, refers to conditions affecting direct gene transfer into rodent muscle in vivo. Felgner, P. L. and G. Rhodes, (1991) Nature 349:351–352, disclose direct delivery of purified genes in vivo as drugs without the use of retroviruses.
The use of direct gene transfer as an alternative anti-pathogen vaccination method has been suggested. Use of direct gene transfer by single injection is suggested as a possible vaccination strategy against HIV. A cellular immune response to HIV gp120 resulting from introduction of plasmid DNA encoding the same into cells is reported to have been observed. PCT International Application Number PCT/US90/01515 published Oct. 4, 1990 discloses methods of immunizing an individual against pathogen infection by directly injecting naked polynucleotides into the individual's cells in a single step procedure. The use of transfecting agents other than lipofectins is specifically excluded from the disclosed methods. The stimulation of inoculated cells is neither disclosed nor suggested. An HIV vaccine is disclosed which consists of the introduction of polynucleotides that encode the viral protein gp120. The operability of this vaccine is not evidenced.